In recent years, user terminals that are used while being held by users or being placed on desks or the like have prevailed rapidly. Examples of those terminals include a tablet, a smartphone, and a tablet PC (Personal Computer). The tablet PC includes a display unit equipped with a touch panel display and a keyboard unit equipped with a keyboard, and is structured to be capable of being switched between a tablet mode and a PC mode as in a clamshell-type PC.
There is known a technique of capturing, when a user uses the terminal while holding it, a position of a user's face with a camera equipped in a smartphone or the like and carrying out image processing based a change in a display angle with respect to the user's face (see Patent Documents 1 and 2).    Patent Document 1: Japanese Patent Application Laid-open No. 2013-246761    Patent Document 2: Japanese Patent Application Laid-open No. 2013-242771